Strap straightening device



Feb. 3, 1970 H. K. OTTO STRAP STRAIGHTENING DEVICE 3 Sheets-Sheet 1 Filed Jan. 22, 1968 H. K. OTTO STRAP STRAIGHTENING DEVICE Feb. 3, 1970 5 Sheets-Sheet 2 Filed Jan. 22, 1968 nvmwroe j/owmzlz 022 0 WMM nrroe/wsrs Feb. 3, 1970 H. K. OTTO 3,493,018

STRAP STRAIGHTENING DEVICE Filed Jan. 22. 1968 3 Sheets-Sheet 3 INVEMTO? fi m/dz 0280 8 YQM/ 07' TOP V675 United States Patent 3,493,018 STRAP STRAIGHTENING DEVICE Howard K. Otto, Berkeley, 11]., assignor to Signode Corporation, a corporation of Delaware Filed Jan. 22, 1968, Ser. No. 699,597 Int. Cl. B2112 1/02; B651) 13/22; B21d 3/12 U.S. Cl. 140147 8 Claims ABSTRACT OF THE DISCLOSURE The strap straightening device forming the present invention acts to compensate for the curl placed in the strap 'by the traction wheel during the feeding and tensioning operation. It essentially comprises a pressure loaded roller that acts on the strap as it is withdrawn through the traction drive assembly. The roller is mounted at one end of a lever that is pivoted intermediate its length. The pressure applied by the roller acts against the concave side of the strap adjacent the traction drive mechanism. The curl imparted to the strap by tensioning it increases as the tension is increased, and the traction wheel, which causes the curl, is so mounted that it is moved toward the backup wheel to provide for increased tension when the tensioning means increases. The movement of the traction wheel, which increases the tension, also acts to move the lever to increase the pressure applied against the concave side of the strap. The pressure applied against the strap deforms the strap to compensate for the curl, thus providing an essentially straight strap after it leaves the pressure roller.

The strap straightening device of the present invention may be used with various strapping mechanisms having means for increasing the tension on the strap as the strap is tensioned about an article. One example of such a strapping mechanism is disclosed in my prior patent No. 3,272,- 113, granted Sept. 13, 1966. Reference to said patent may be had for a more complete disclosure of the structure shown in the drawings of the present application, which does not specifically relate to the strap straightening mechanism.

In strapping machines of the type disclosed herein, the strap is fed between a driven traction wheel and a backup wheel, and after the strap is looped around the material to be bound, it is tensioned to form a tight bundle by reversing the direction of rotation of the traction wheel. The traction wheel usually has teeth to provide traction. The teeth bite into one side of the strap and displace some of the metal, thereby making the side engaged by the teeth longer than the side engaged by the smooth backup wheel, resulting in a curled strap with the smooth side being concave.

The curl is objectionable because the retracted portion of the strap, which is curled, must be fed through a chute for the next strapping operation. If provisions are not made to straighten the strap, it will be difficult to rethread the strap through a chute, which could substantially increase the cycling time, create jamming, or otherwise reduce the efiiciency of the strapping operation. In accordance with the present invention, a pressure-loaded roller is applied against the concave side of the strap, which roller is adjusted so that it deforms the strap just enough to eliminate the curl and thus straighten the strap.

During the strapping operation, the amount of tension required to pull the strap increases as the strap is tightened around the bundle and the resistance to the tensioning increases. Before the strap extending around the bundle is tightened to the desired extent, the resistance to the tensioning is often great enough to cause the traction wheel to slip. It is then necessary to increase the driving force applied to the traction wheel.

The driving force of the traction wheel is increased by moving the traction wheel closer to the backup wheel, thus causing the teeth of the traction wheel to bite deeper into the strap. The deeper bites displace more of the metal and thus increase the degree of curl. The pressure applying roller is mounted on a lever operatively connected to a motor mount in which the traction wheel is mounted. Thus, when the motor mount is rotated to move the traction wheel closer to the backup wheel to increase the tension, it also moves the lever, and thus increases the pressure applied by the roller proportionately to the increase in tension. In essence, the curl put in the strap by the tension wheel is taken out by the proportionate increase in counteracting forces imposed by the roller acting on the curved strap.

Suitable structure by means of which the above mentioned advantages are attained will be described in the following specification, taken in conjunction with the accompanying drawings, showing a preferred embodiment of the invention, in which:

FIGURE 1 is a side elevational view of a power strapping machine of the type in which the strap straightening device may be embodied;

FIGURE 2 is an enlarged side view, partly in section and partly in elevation, of the strap straightening device applied to a tensioning mechanism;

FIGURE 3 is a cross-sectional view, taken generally along the line 33 of FIGURE 2;

FIGURE 4 is a cross-sectional view, taken generally along the line 4-4 of FIGURE 2 and showing some of the related structure in elevation;

FIGURE 5 is a cross-sectional view, taken along the line 5-5 of FIGURE 3; and

FIGURE 6 is an enlarged fragmentary elevational view of the traction wheel and backup wheel with a section of strap therebetween.

In FIGURE 1, a coil 11 of metal strip is positioned on a suitable support 12 with a chute 13 guiding a metal strap 14. A feeding and tensioning mechanism 15 mounted adjacent the support 12 feeds the metal strap 14 from a reel (not shown) into the chute, through-the center opening of the coil 11, and then into overlapping relationship to form a loose loop around the material to be bound. The portion of the metal strap retracted through the tensioning device to tighten the strap around the metal coil is straightened so that it can be readily fed through the chute for the next binding operation.

As shown best in FIGURE 2, the feeding and tensioning mechanism 15 comprises a traction wheel 16 and a backup wheel 17 that engage opposite sides of the strap 14. The peripheral surface of the backup wheel may be smooth, but as shown is provided with a circumferential groove 18, as shown in FIGURE 6, to provide the strap with a reinforcing rib 19. The peripheral surface of the traction wheel 16 has teeth 21 projecting therefrom to pro vide improved traction for the strap. The traction wheel is mounted on a shaft 22 that is journaled in bearings 23 for rotation about an axis 24.

The shaft 22 is driven by a reversible motor 25 that is carried by a motor mount 26. The motor mount is journaled in bearings 27 for rotational movement about an axis 28 parallel to and spaced from the axis 24. The backup Wheel 17 is mounted on a shaft 29 journaled in bearings 31 for rotation about a fixed axis 32. As viewed in FIGURE 2, the eccentric mounting of the shaft 22, relative to the axis 28, causes the traction wheel 16 to be moved toward the backup wheel 17 by counterclockwise rotational movement of the motor mount. The traction Wheel is moved away from the backup wheel 17 by clockwise rotational movement of the motor mount.

As shown in FIGURE 2, a spring 33 urges the motor mount 26 counterclockwise about its axis 28, and thus 'ges the traction wheel toward peripheral engagement ith the backup wheel to facilitate gripping of the strap lring the feeding operation. A handle 34, fixed to the ount 26, is movable clockwise against the action of the rring 33 to separate the traction wheel from the backup heel far enough to allow the strap 14 to be threaded :tween the peripheral surfaces of the two wheels.

The traction wheel is moved to press the strap against re backup wheel and the shaft 22 is rotated counterclockise until the strap is looped loosely about the material r be bound. The free end of the strap is held against rovement by any suitable gripping mechanism, and the rotor 25 is reversed to retract the last fed portion of re strap and to tension it around the bundle. When the :sistance to the tension increases, the reaction rotates the rotor mount 26 counterclockwise about its axis 28, as escribed in my prior patent, and moves the traction wheel loser to the backup wheel to increase the traction force gainst the strap. The increase in the traction force causes 1e teeth 21 to bite deeper into the strap. The deeper enetration of the teeth into one side of the strap dislaces more metal and thus increases the degree of curva- 1re of the strap.

The curl of the strap is counteracted by a strap straightning device adapted to apply pressure against the conave side of the strap adjacent the tensioning mechanism. The strap straightening device is initially adjusted to exert 1st enough pressure against the concave side of the strap a deform it to the same extent, but in the opposite direcion to which it is curled when it is fed forwardly through he tensioning device. The amount of curl in the forward eed of the strap depends upon the force of the spring 33 .nd its mechanical advantage. When the strap is retracted, he depth of penetration by the teeth 21, and the conseuent curl, is the same as in the forward feed until the lack is taken out. As the tension increases, the tensionng mechanism becomes self-energizing, as described in my rior patent. Therefore, the pressure against the concave ide of the strap must be increased to take out the curl so mposed to straighten the strap.

The strap straightening device comprises a lever 35 )iVOtCd intermediate its length, as indicated at 36. A pres- :ure roller 37 is rotatably mounted near one end of the ever. A nose piece 38, urged clockwise by a spring 39, is reld in spaced relationship to the peripheral surface of he traction wheel 16 and has its lower surface curved, as ndicated at 38. An insert 40, having its upper surface :urved, as indicated at 40', cooperates with the nose 38 guide the strap 14 when it is initially threaded between :he traction wheel and the backup wheel.

When the motor mount 26 is moved counterclockwise, as viewed in FIGURE 2, to increase the tension on the :trap 14, the lever 35 is moved counterclockwise by mechrnism hereinafter described. The counterclockwise movenent of the lever 35 increases the pressure of the roller 57 proportionately to the increase in the curl, so that be retracted portion of the strap is straightened.

Turning now to the connection between the motor mount 26 and lever 35, it is seen that the underside of the lever 35 has a notch 41 into which the cylindrical head 42 of a screw 43 fits (see FIGURE 4). The screw extends through an aperture 44 in the lever 35 and through an aperture 45 in a bar 46 extending at right angles to the lever. The other end of the bar 46 is rigidly secured to a bar 47 and is in turn rigidly secured to the motor mount 26. The bar 47 extends through an opening 48 in the housing 49 in which the bearings 27 are mounted (see FIGURES 3, 4, and The opening 48 is elongated to permit limited movement of the bar 46 as the motor mount 26 is moved rotationally.

A compression spring 51 encircling the screw 43 above the bar 46 urges the bar 46 toward the lever 35. One or more washers 52 may be interposed between the lever 35 and the bar 46 to vary the initial setting of the straightening effect. Nuts 53 are threaded on the screw 43 to also vary the straightening effect.

Counterclockwise rotational movement of the motor mount 26 moves the bar 46 in the same direction. If the spring 51 is so tight that it cannot be compressed further, the movement of the bar 46 will move the screw upwardly, as viewed in FIGURE 2. Upward movement of the screw 43 will move the outer end of the lever 35 in a counterclockwise direction and force the roller 37 downwardly against the strap 14 to increase the pressure. With proper adjustment of the spring 51, and proper number of washers 52, the increase in pressure against the strap 14 will deform the strap to counteract the increase in curl of the strap that is caused by the increased tension on the strap, and will straighten the strap as it is retracted from the tension mechanism.

While the arrangement shown is designed to contact the concave side of the strap, it is, of course, Within the ambit of this invention to employ a mechanism which would contact the convex side of the strap while performing the strap straightening function.

Although a preferred embodiment of the invention has :been described in considerable detail, it will be understood that the description thereof is intended to be illustrative, rather than restrictive, as many details of structure may be modified or changed Without departing from the spirit or scope of the invention. Accordingly, it is not desired to be restricted to the exact structure described.

What is claimed is:

1. A device for straightening strap that is curled longitudinally to varying degrees by tensioning means, the degree of curl of said strap depending upon the tension force applied thereto, said device comprising pressure applying means engaging a surface of said curled strap, and means responsive to the tensioning means for automatically adjusting said pressure applying means proportionately to the variations in the tension applied to said strap, whereby said strap is bent to an extent sufficient to compensate for the curl imparted to it by said tensioning means.

2. A device as set forth in claim 1 in which the pressure applying means engages the concave side of the curled strap during the strap straightening operation.

3. A device as recited in claim 2, in which said adjusting means includes a lever pivoted intermediate its length, a roller rotatably mounted adjacent one end of said lever and positioned to contact the concave side of said curled strap, and means interconnecting the other end of said lever and said tensioning means.

4. A device as recited in claim 2, in which said tensioning means includes a backup wheel mounted on a fixed axis, a tension wheel mounted on a movable axis parallel to said fixed axis and an eccentrically mounted support for said tension wheel to move said tension wheel toward said backup wheel to increase the bite of said tension Wheel into said stra-p, said pressure applying means comprises a lever pivoted intermediate its length, a roller mounted adjacent one end of said lever and positioned to contact the concave side of said strap, and means connecting the other end of said lever to said support.

5. A device as recited in claim 4, in which said backup wheel has a circumferential groove in its peripheral surface, whereby a longitudinally extending reinforcing ridge is formed in said strap during the tensioning operation.

6. In combination with a strap tensioning means that curls the strap proportionately to the tension applied thereto and has a motor mount rotatable to vary the energizing force applied by the tensioning means to the strap, a strap straightening device comprising pressure applying means engaging a surface of said strap and bending said strap to an extent sufiicient to compensate for the curl imparted to said strap by said strap tensioning means, and means operatively connecting said pres sure applying means to said motor mount, whereby rotation of said motor mount varies the force applied to the surface of said strap proportionately to the tension applied to said strap to straighten the strap.

7. A structure as set forth in claim 6 in which the pressure applying means contacts the concave side of the strap whereby the motor mount varies the force applied thereto.

8. The structure recited in claim 7, in which said pressure applying means comprises a lever pivoted intermediate its length and a roller rotatably mounted adjacent one end of said lever and positioned to contact the concave side of said strap when it leaves the tensioning means, and means for operatively connecting said pressure applying means to said motor mount comprising a member rigidly secured to said motor mount, screw means extending through said member and the opposite end of said lever, and spring means pressing said met ber against said lever whereby movement of said men ber moves said lever about its pivot to increase the for applied by the roller against the strap to straighten sam References Cited UNITED STATES PATENTS 3,146,694 9/1964 Staron et al. 140-14 3,215,064 11/1965 Koehler 14014 CHARLES W. LANHAM, Primary Examiner LOWELL A. LARSON, Assistant Examiner US. Cl. X.R. 72.183; 10032 

